Can Synthetic Inertia from Wind Power Stabilize Grids?

p1110724As renewable power displaces more and more coal, gas, and nuclear generation, electricity grids are losing the conventional power plants whose rotating masses have traditionally helped smooth over glitches in grid voltage and frequency. One solution is to keep old generators spinning in sync with the grid, even as the steam and gas turbines that once drove them are mothballed. Another emerging option will get a hearing next week at the 15th International Workshop on Large-Scale Integration of Wind Power in Vienna: synthetic inertia.

Synthetic inertia is achieved by reprogramming power inverters attached to wind turbines so that they emulate the behavior of synchronized spinning masses.

Montréal-based Hydro-Québec TransÉnergie, which was the first grid operator to mandate this capability from wind farms, will be sharing some of its first data on how Québec’s grid is responding to disruptive events such as powerline and power plant outages. “We have had a couple of events quite recently and have been able to see how much the inertia from the wind power plants was working,” says Noël Aubut, professional engineer for transmission system planning at Hydro-Québec. Continue reading

Wind Could Provide Over 26% of Chinese Electricity by 2030

Last month I argued that the primary reason Chinese wind farms underperform versus their U.S.-based counterparts is that China’s grid operators deliberately favor operation of coal-fired power plants. Such curtailment of wind power has both economic and technical roots, and it has raised serious questions about whether China can rely on an expanding role for wind energy. New research published today appears to put those concerns to rest, arguing that wind power in China should still grow dramatically.

The report today in the journal Nature Energy projects that wind energy could affordably meet over one-quarter of China’s projected 2030 electricity demand—up from just 3.3 percent of demand last year.

In fact the researchers, from MIT and Tsinghua University, project that modest improvements to the flexibility of China’s grid would enable wind power to grow a further 17 percent. That, they argue, means that China’s non-fossil resources could grow well beyond the 20 percent level that China pledged to achieve under the Paris Climate Agreement. Continue reading

Does Hawaii Need a Unified Grid?

Power cables to Oahu could reduce curtailment of Maui wind farms. Credit: First Wind

Since 2013, a big mainland energy firm has been raring to build Hawaii’s first inter-island power cable, arguing that only a unified power grid can enable the renewable energy developments needed to break Hawaii’s addiction to imported petroleum. Now that big outsider—Juno Beach, Florida-based NextEra Energy—is trying to absorb Hawaii’s power providers in one big bite.

In December, NextEra announced plans for a friendly $4.3 billion acquisition of Hawaiian Electric Industries, which owns the vertical monopolies that run the archipelago’s island grids (with the exception of Kauai’s). Observers debating what the acquisition would mean for Hawaii’s electrical future see at least three quite distinct outcomes:

  • NextEra secures Hawaiian Electric and builds cables to unify its assets, unleashing renewable energy development
  • NextEra’s bid for Hawaiian Electric is squashed by officials with longstanding mistrust of outside interests, and the island utilities proceed on their own
  • NextEra wins approval for the acquisition but drops its cable ambitions, focusing instead on bringing liquefied natural gas to Hawaii to repower Oahu’s oil and coal-fired generators

Interconnecting the islands is an idea that dates all the way back to an 1881 meeting in New York City between Hawaii’s then-King Kalakaua and Thomas Edison. Kalakaua’s officials asked Edison if electricity could be generated from the Big Island’s active volcano and delivered via subsea cable to Oahu to bring electric light to Honolulu, thus sparing Hawaii greater dependence on Australian coal. Edison said the scheme could work, according to a report by the New York Sun, but demurred that it, “would cost so much, that’s all.”

134 years later, one hears essentially the same arguments for and against a unified Hawaiian grid. Proponents such as NextEra and the Hawaii State Energy Office say Oahu must hook up to its neighbors’ grids because it lacks the renewable resources needed to meet even half of its power demand—over 7,500 gigawatt-hours (GWh) per year, or nearly three-quarters of the state’s total.

Hawaii’s other islands, by contrast, have renewable potential to spare, says a 2010 analysis commissioned by the U.S. Department of Energy’s National Renewable Energy Lab. Lanai and Molokai could each generate over 1,000 GWh per year of wind power; Maui has over 2,000 GWh of viable geothermal, wind, and solar resources; and Hawai’i (better known as the Big Island) has over 6,000 GWh of geothermal potential. Sharing these resources with Oahu via subsea cables, the authors concluded, was the only way to meet Hawaii’s goal to push renewables to 70 percent of the power supply by 2030.

In 2013, NextEra proposed to start with a 180-kilometer-long, high-voltage direct current (HVDC) link between Maui and Oahu dubbed NextGrid Hawaii. Last year, Pacific Business News reported that NextEra had secured property in downtown Honolulu for the converter station where NextGrid’s pair of 200-megawatt cables would come ashore and link up with Oahu’s AC grid.

NextGrid would cost an “enormous” $600-800 million, according to Pacifc Business News, but NextEra said it would save the islands’ utilities at least $4.8 billion over its first 40 years of operation. The State Energy Office conservatively pegs net savings to consumers at a more modest $423 million, plus $128 million in environmental benefits.

One source of savings is avoided ‘curtailment’ of wind farms on Maui, which already produce more power at times than the local grid can handle. Hawaiian Electric’s Maui subsidiary ‘curtailed’ 20.6 GWh of wind generation last year. (Kauai’s utility expects to begin curtailing solar power generation this year.)

The promise of better renewable energy utilization earned NextEra support from some environmental groups. “We’re stronger together,” says Jeff Mikaluna, executive director for the Honolulu-based Blue Planet Foundation. In addition to better integrating renewables, says Mikaluna, tying the islands together should also reduce the need to keep fossil fueled power plants running in reserve.

NextGrid also appears to be spurring interest in cables to other islands, such as the Big Island. That island’s biggest landholder, the historic Parker Ranch, says a cable to Oahu could benefit a pumped hydroelectricity storage project it is developing. “Parker Ranch could enable a large-scale storage solution as part of an integrated statewide grid,” wrote Parker Ranch CEO Neil Kuyper inan August 2014 press release.

Of course, as is usually the case for transmission proposals, the idea of inter-island cables also has its critics. Some question, as Thomas Edison did, whether cables will really pencil out economically. Henry Curtis, executive director for Honolulu-based environmental advocacy group Life of the Land and a blogger on energy issues, says technical challenges associated with laying power cable over steep subsea slopes could inflate project costs.

Curtis also questions the cables’ environmental benefits, and highlights potential environmental harm. NextEra’s Maui-Oahu cable, for example, would traverse a humpback whale sanctuary.

And cables might ultimately prove unnecessary if advances in grid and power generation technologies expand Oahu’s indigenous renewable resources. Smarter inverters, for example, are helping Oahu’s grid cope with increasing levels of distributed solar energy. Curtis says more energy may be available just offshore, citing the ocean thermal energy converter currently being tested by Hawaii-based Makai Ocean Engineering.

Distributed generation advocates, meanwhile, are raising alarms about the track record of NextEra subsidiary Florida Power and Light (FPL), the utility that serves most of Florida. In December, Greentech Media noted that Florida ranks 29th in the country for overall renewable energy development, and blamed FPL for the sun-soaked state’s shortage of solar power: “It’s not for lack of sunshine; it’s lack of policy. Florida has no renewable standard—FPL has crushed every effort to establish one.”

Energy analyst William Pentland raised similar alarms in Forbes last month. “Hawaiians should think long and hard about NextEra’s track record in the Sunshine State before approving any merger,” writes Pentland.

NextEra is, for its part, playing the grid unification card close to its chest as Hawaii’s regulators weigh its offer for Hawaiian Electric. One thing appears certain: NextEra will face heightened expectations to deliver on Hawaii’s renewable energy aspirations if the acquisition goes through.

Blue Planet Foundation’s Mikaluna says Hawaiian Electric was saying what state leaders wanted to hear at the state capitol earlier this week. During a hearing on a bill proposing a 100-percent-renewables standard for Hawaii’s utilities for 2040, Hawaiian Electric’s representative abandoned the utility’s traditional tack. Rather than hedging on the prospects for zeroing-out fossil fuel consumption, the new message was ‘How about 2050?’ “That’s a first,” says Mikaluna.

This post was created for Energywise, IEEE Spectrum’s blog on green power, cars and climate

Floating Wind Turbines Headed for Offshore Farms

PrinciplePower.WindFloatFloating wind power is no longer science fiction. Promising results from five test platforms operating worldwide—including three in Japan—are turning into project plans for a first generation of floating wind farms. Industry analyst Annette Bossler, who runs Bremen, Maine-based Main(e) International Consulting, predicts that the number of test platforms will nearly double over the next two years and that commercialization is within site. “By 2018-2019 you will start to see the first really large-scale commercial use of floating platforms,” predicts Bossler.

Putting wind turbines on offshore platforms akin to those developed for the petroleum industry provides a means of exploiting high-quality offshore winds—which are stronger and more consistent than onshore winds—in waters too deep for today’s bottom-fixed foundations. Continue reading

Broken Bats: Wind Power and the Damage Done

Last year, IEEE Spectrum profiled an ultrasonic alert for wind farm operators designed to let them know when bats are nearing their turbines. The potentially bat-saving technology can’t be ready soon enough according to this week’s issue of the journal Bioscience. University of Colorado ecologist Mark Hayes estimates that at least 600 000 and possibly more than 900 000 bats were killed by wind turbines last year in the U.S.

Hayes’ report is a statistical reassessment of data on bat carcasses found at wind turbine sites. His figure lends credence to a March 2013 mortality estimate of 880 000 deaths per year by Sacramento-based ornithologist and consultant Shawn Smallwood. That figure was well beyond previous estimates, which had ranged as low as 33 000. “My estimates, using different methods and data, bracket Smallwood’s 888 000 estimate,” writes Hayes in an e-mail to Spectrum. Continue reading

Building-in a Force of Nature

Turbine House: Design by Michael Pelken & Thong Dang

Turbine House: Michael Pelken & Thong Dang’s residence with horizontal-axis wind turbine

As design teams work toward harnessing air flows around buildings, they are producing some intriguing structures. But just how viable is wind power as a source of on-site renewable energy?
By Peter Fairley

Wind power is the fastest-growing source of megawatts thanks to the jumbo-jet-sized turbines sprouting en masse worldwide. But it also has a significant presence in the city, where gusts regularly send umbrellas to landfills. Rather than considering it a nuisance, architects increasingly view urban wind as a renewable resource for on-building power generation.

Building-integrated wind power (BIWP)—wind turbines mounted on or incorporated within an occupied structure—may lack wind farms’ economies of scale. But like the leading source of on-building renewables—photovoltaics (PVs)—wind turbines offer some advantages in architectural applications. No roads get cut through wilderness to erect towers, and they deliver electricity without power lines and transmission losses. Wind turbines are also attractive to designers and clients looking to express a commitment to sustainability.

Such benefits provide potential for dramatic growth, says mechanical engineer Roger Frechette, principal in the Washington, D.C., office of Interface Engineering. “If there’s data showing that BIWP works and testimony that it’s a good thing to do, there will be an explosion,” he predicts…

Published in the April 2013 issue of Architectural Record Magazine. Read the whole story.

A Mighty Extreme Wind for Offshore Turbines

In January we reported that winds across the Northern continents were losing some of their punch, and that climate change threatened to weaken them further — altogether bad news for wind power. In stark contrast, Australian researchers report today in the journal Science that gusts are accelerating over Earth’s oceans.

Unfortunately the trend offers offshore wind power a mixed bag: stronger but also more dangerous winds. “Mean wind conditions over the oceans have only marginally increased over the last 20 years. It is the extreme conditions where there has been a larger increase,” says Ian Young, vice chancellor at the Australian National University in Canberra and principal author of today’s report. Continue reading